1. Field of the Invention
The present invention relates to a three-dimensional volumetric display apparatus, and more particularly, to a three-dimensional volumetric display apparatus which projects a surface texture image of a volumetric shape model onto the volumetric shape model to perform three-dimensional volumetric display.
2. Background Art
When plural people discuss any one subject, a conference has been actively held due to collaboration which can obtain a better result by sharing information, intention, or idea with one another. At this time, for the purpose of exhibiting data in a visible and understandable form, an opportunity of using a three-dimensional volumetric display (three-dimensional volumetric display device) has increased.
A stereoscopic display technology has been suggested in various forms. As a representative example, there are the following polarizing glasses or a lenticular method.
The polarizing glasses mainly apply to a projection type stereoscopic display. Using two projectors, a left parallax image is projected onto a screen by one projector in a vertical deflection state and a right parallax image is projected onto the screen by the other projector in a horizontal deflection state. Provided are glasses in which a deflection filer for transmitting horizontally deflected light and blocking vertically deflected light is attached to a right lens and a deflection filter for transmitting vertically deflected light and blocking the horizontally deflected light is attached to a left lens. These glasses can cause an object to be stereoscopically viewed because the left parallax image is incident to a left eye and the right parallax image is incident to a right eye. In this method, since special glasses such as the polarization glasses must be used, there is a problem that a natural work style may be damaged. Furthermore, since only a stereo image viewed from any view point is displayed and parallax is not varied although a position of the eye is changed, there is a problem that stereoscopic display is observed with incongruity.
Furthermore, the lenticular method mainly applies to a stereoscopic display liquid crystal panel. An object is stereoscopically viewed by installing a lenticular lens for covering two pixels at the front side of the liquid crystal panel in an array, enabling a pixel for displaying a left parallax image to be incident to a left eye, and enabling a pixel for displaying a right parallax image to be incident to a right eye. In this method, there is a merit that special glasses are not needed. However, since parallax is not varied, there is a problem that stereoscopic display is observed with incongruity, similar to the polarization glasses. Since a distance between a point which can be stereoscopically viewed (eye position) and an optimal position is very narrow, for example, about ±10 mm, the eye must be always fixed to any position, and thus eyestrain or physical fatigue is apt to occur. In addition, simultaneous stereoscopic viewing is limited to each individual person and information on data can not be shared with participants.
As such, the polarization glasses or the lenticular method is not suitable as the stereoscopic display method for the collaboration which is performed by many people. Accordingly, a volumetric display method which can display an object as if the object is placed there wherever viewing the object has been suggested. Several representative examples are as follows.
First, a laminated cross-sectional projection method (Patent Document 1) laminates liquid crystal cells of a transparent state or a diffusion state by electrical driving and sequentially projects a cross-sectional image of a display object by a projection device only one liquid crystal cell is in the diffusion state and the other liquid crystal cells are in the transparent state. The liquid crystal cell of the diffusion state is electrically scanned in sequential and corresponding cross-sectional image is projected by the projection device in synchronization with the scan, thereby performing three-dimensional volumetric display. In this method, since the projected image is the cross-sectional image, it is not possible to represent a surface texture. In addition, the displayed stereoscopic image becomes a phantom image in which an inner image is viewed and thus the object is stereoscopically displayed different from an actual object.
Furthermore, a method of displaying a three-dimensional shape with a plurality of pins (Patent Document 2) arranges the plurality of pins each having an actuator for vertically sliding the pin in a matrix and vertically moves the plurality of pins by control of a computer, thereby displaying the three-dimensional shape. Also, the pin is formed of a transparent material, a figure is formed on a pin substrate by display from a lower side of the substrate of a pin matrix for displaying the shape, and the pin matrix is viewed from an upper side to identify the figure. In this method, it is not possible to efficiently represent a surface texture of an object.
In addition, a method of vertically moving a plurality of image display elements (Patent Document 3) vertically moves the plurality of image display elements arranged in two dimensions in an arrangement surface based on three-dimensional information, changes the arrangement surface, and emits light from the surface with desired color and brightness. Also, a display surface of the image display element is covered by a screen and the color and brightness signals of each image display element are projected onto the screen. Even in this method, it is not possible to efficiently represent a surface texture of an object.
[Patent document 1] JP-A-2002-139700
[Patent document 2] Japanese Patent Publication No. 2736908
[Patent document 3] Japanese Patent Publication No. 3127447